Process of drying leather and simi



May 31, 1938. A. o. HURXTHAL PROCESS OF DRYING LEATHER AND SIMILARLYTAUTLY STRETCHED UNITS Original Filed Jan. 29, 1936 3 Sheets-Sheet 1 ON\N Z I M g Ma 31, 1938. A. o. HURXTHAL PROCESS OF DRYING LEATHER ANDSIMILARLY TAUTLY STRETCHED UNITS Original Filed Jan. 29, 1956 3Sheets-Sheet 2 May 31, 1938. A. o. HURXTHAL PROCESS OF DRYING LEATHERAND SIMILARLY TAUTLY STRETCHBD UNITS Original Filed Jan. 29, 1956 3Sheets-Sheet I5 Reisaued May 31, 1938 PROCESS OF DRYING LEATHER ANDSIMI- LARLY TAUTLY STRETCHED UNITS Alpheus 0. Hurxthal, Philadelphia,Pa., assignor to Proctor & Schwartz, Incorporated, Philadelphla, Pa., acorporation of Pennsylvania Original No. 2,109,425, dated February 22,1938, Serial No. 61,392, January 29, 1936. Application for reissue March25, 1938, Serial No.

1 Claim.

This invention relates to a new and improved method of drying animalhides, leather or corresponding units of other materials, particularlythose of irregular sizes and contours, which are 5 normally stretched onframes or boards individual to the units and wherein the units aresecured to the drying and stretching frames by toggles or other deviceswhich grip each unit at spaced intervals around its edge.

In the case of leather, i. e. pretanned animal hides of different kinds,it. is customary while the hides are still in a wet condition to hangthe hides or skins on poles or hooks in dry lofts or to stretch eachunit on a frame comprising a wire mesh screen or perforated sheetcapable of receiving the hooks of the toggles which are clamped to theedges of the unit to draw, stretch and hold the unit tightly and evenlyover and throughout its entire area.

2 The loaded frames are usually inserted into a drier in relativelyclose laterally spaced parallel relation to each other. Drying iseffected by air blowing from one side or end of the drying chamberacross and between the plurality of frames, with the air moving in thedirection of the plane of each frame and across the unit carried therebyfrom one edge thereof toward the other edge thereof.

Under the above noted process or system, that edge of the unit nearestthe source of the drying air, and with which the air contacts first,begins to dry before any other portion of the unit and this unevendrying progresses across the unit in accordance with the direction inwhich the air travels. Consequently, that edge of the unit which liesfurthest away from the source of the drying air dries last and beforethis edge is completely dry the opposite edge, that is, the edge nearestthe source of drying air has become overdried resulting in that edge andthe adjacent portion of the unit becoming harsh while the last driedportion, which is dried to the proper extent, is relatively soft andpliable.

The progressive drying of the unit from one side toward the oppositeside thereof, in addition to the above, is responsible for detrimentalstrains being set up in the unit itself. As the unit dries it shrinksand where the drying is progressive from one side to the other theshrinking likewise follows from one side to the other, thus creatingundesirable. strains, under which the unit is placed by such unevenshrinkage, and which frequently causes the leather to pull loose fromthe toggles with a resultant damage to the leather at and adJacent theedges of the unit.

(Cl. S t-24) Subsequent to the above noted drying of the skins the skinsare put through an operation commonly called sammying. This operationmerely consists of dampening the hides or skins with water and layingthem away in a pile with or without sawdust between the hides to permitthe moisture to soak through and mellow the skins or hides.

Subsequent to the sammying" operation the skins or hides are put throughanother operation commonly referred to as staking. This operation merelyconsists in the pulling out of the leather between an iron anvil and anagate roller. During this operation the skins are in a very moistcondition and are again stretched on frames and dried in the mannerabove noted after the staking operation has been completed-.

After skins have been dried subsequent to the staking operation theskins are put through what is commonly known as a seasoning operationwhich is simply a surface finishing and during which there is a verysmall amount of moisture in the skins.

After' seasoning the hides are hung on poles or hooks prior to beingbrushed and trimmed ready for market and during which time the slightamount of moisture present during the seasoning operation is evaporatedby natural or artificial means.

The present invention is intended for use in the drying of the hides atany stage in the operation prior to the seasoning in which the.hidescontain a relatively great amount of moisture requiring a considerablelength of time for its removal from the hides prior to the hides beingsubjected to the next step of the processing of v the hides and in whichthe hides are subject to the detrimental drying strains noted above.

The object of the present invention is to cause s the drying air toimpinge upon all parts of the unit simultaneously, in a directionsubstantially perpendicular to the plane of the unit, whereby even anduniform drying and shrinking of the unit is accomplished at all pointsthroughout its entire area at the same time.

Under the method forming the subject matter of the present invention theunit dries in approximately one-third the time required for drying thesame units under the old method above .described. In the drying ofleather and similar units, one of the greatest handicaps of the industryhas been the expense involved in -the provision of sufficient numbers offrames and toggles. Under the method forming the'subject of the presentinvention, and wherein the drying time is reduced that each frame andits complementof toggles is available for use three times as often asunder the old method. Consequently, only one-third of the number offrames and toggles will be required for drying a predetermined number ofunits orthree times as many units may be dried in the same time and withthe same equipment as was formerly required for the drying of the lessernumber of units.

Under the old system in order to lessen the unequal drying of the unitsand the detrimental effects thereof it was necessary to employ some formof humidifying apparatus inthe drier for retaining or supplying moistureto the air in circulation. This condition lengthened the time necessaryto dry the units, whereas under the system or process forming thesubject of the present invention it is possible to extract the moisturefrom the air in circulation and to impinge the dry air against theunits, thus materially reducing the time necessary for the drying ofeach unit and at the same time eliminating the detrimental effects ofthe strains normally set up by the unequal drying and shrinking underthe old method.

The drying of leather or other units in accordance with the principlesof the present invention may be readily carried on in an apparatus suchas that disclosed in the accompanying drawings, of which: 7

Fig. 1 isa vertical longitudinal section of the drier;

Fig. 2 isa sectional plan view taken on the line v 2-2, Fig. 1; and

- her 3 at the opposite end, a circulating chamber 4 above the chambers2 and 3 and extending 1ongitudinally of the drier and a lowercirculating chamber 5 extending longitudinally of the casing beneath thechambers 2 and 3.

The circulating chambers 4 and 5 communicate at one end with the airconditioning chamber 2, through heating or cooling units 6 and l bywhich the air in circulation may be heated or cooled or the entrainedmoisture removed.

The air conditioning chamber 2 and drying chamber 3 are separated byasuitable partition 8 in which is formed a circular opening 9. An airimpeller in the form of a fan H) in the present instance is rotatablymounted in the opening 9 and rotated in any suitable manner; forexample, by an electric motor ll mounted in the air chamber 2.

The chamber 3 is provided with a plurality of vertical partitions l5which are of a foraminous nature throughout and which divide the chamberinto frame receiving compartments l6, It, in which the units of materialto be dried are placed, and intermediate channels I! which communicateat one end with an air space [8 formed at the 'one end of the dryingchamber 3. The interiors of the compartments l6 communicate at theirtops and bottoms respectively with the upper and lower circulatingchambers 4 and 5. The vertical partitions l5 as illustrated in thedrawings are provided with perforations is over their entire areas.

The leather or other units a: are stretched *tautly on suitable dryingframes which each include in the present instance a perforated plate 20having openings 20a over its entire surface for receiving the hooks ofthe toggles (not shown) which, as is well known in the art, grip theleather or other unit at desired points around the edges of the unit andsupport the unit in laterally spaced substantially parallel relation tothe perforated plate 28.

Each plate 20, is hung within a frame 2| by suitable straps 22, and.each frame 2| in turn is pivoted at its opposite sides, as illustratedat 23, 23, within a supporting frame 24. Each supporting frame 24 isprovided with wheels 25 arranged to run on overhead tracks 26 mounted inthe upper chamber 4 of the casing i.

Each of the frames 2! is provided with an end plate 21, said end platescombining with vertical plates 28, 28 at the receiving end of the drierto form an end Wall on the drier when the drying frames are in positionwithin the drier.

As shown in Fig. 2, the partitions l5, l5 are spaced apart adjacent theair space l8 to form the mouths of the channels I! and converge towardthe opposite end of the drier to progressively reduce the width of eachchannel l1. At the last said end of the drier each converging pair ofpartitions 15 are joined together and to one of the end plates 28.

With the fan H) in operation, the air is moved or drawn out of the endcompartment 2 and propelled into the air space is, at the one end of thechamber 3, and moves longitudinally of the drier from the air space l8into the wide ends of the channels I1. The converging relation of theperforated partitions I5 traps the longitudinally flowing air and causesit to move out of the channels I! substantially at right angles theretoand perpendicular to the partitions l5, entering the compartments Hifrom opposite sides thereof and impinging upon the exposed surface ofthe unit ac carried by each of the plates 29 within each compartment 16.

In some instances, there may be a unit a: mounted on each side of eachplate 20. However, whether there is a unit on but one side or a unit oneach side of each plate, the air passing from the channels l1 into thecompartment IE will impinge upon the one or both units .1. at all pointsover the entire area thereof and substantially at right angles to theplane thereof, whereby uniform drying at all points throughout the areaof each unit occurs simultaneously.

The air after impinging upon the units passes upwardly and downwardlyinto the upper and lower compartments 4 and and returns to the chamber 2through the conditioning apparatuses 6 and I, as previously noted; for arepeat of the cycle.

While the drawings show a largenumber of relatively small holes ii! ineach of the walls l5 for simultaneously projecting a large number ofjets of air against the surface of the unit being dried, it is withinthe scope of the present invention to use a smaller number of largerholes distributed over the area of the unit or a single large hole atthe center of the surface of the unit to project the air against theunit substantially at the center thereof or at a number of points aboutthecenter of the unit to cause the air to move from the jet or jets incontactwith the surface of the unit toward the marginal edges thereofand whereby a uniform drying of the unit may be accomplished. However,the large number of small jets is preferable.

I claim:

Themethod of drying wet tanned hides prior to seasoning or otherfinishing treatment which consists in stretching a hidein all directionsoutwardly from the central area thereof toward the marginal edges of thehide, securing the edges of the stretched hide to a suitable support toresist subsequent shrinkage of the hide, and

ALPHEUS O. HURXTHAL.

